Issue 1:
Playing around with 1.6.0-beta on MacOS I ran into this:

using TypedPolynomials
@polyvar x y
[x,y,0]

when the REPL tries to print the Vector:

3-element Vector{Term{Int64, Monomial{(x, y), 2}}}:

signal (4): Illegal instruction: 4
in expression starting at none:0
_zip_iterate_all at ./iterators.jl:361 [inlined]
iterate at ./iterators.jl:351 [inlined]
_show at /Users/felixger/.julia/packages/MultivariatePolynomials/bsuXE/src/show.jl:64
_show at /Users/felixger/.julia/packages/MultivariatePolynomials/bsuXE/src/show.jl:98 [inlined]
show at /Users/felixger/.julia/packages/MultivariatePolynomials/bsuXE/src/show.jl:13 [inlined]
show at /Users/felixger/.julia/packages/MultivariatePolynomials/bsuXE/src/show.jl:20
unknown function (ip: 0x16474189f)
jl_apply_generic at /Applications/Julia-1.6.app/Contents/Resources/julia/lib/julia/libjulia-internal.1.6.dylib (unknown line)
#sprint#384 at ./strings/io.jl:103
unknown function (ip: 0x16473e6aa)
sprint##kw at ./strings/io.jl:101 [inlined]
alignment at ./show.jl:2528 [inlined]
alignment at ./arrayshow.jl:68
unknown function (ip: 0x16473e3a2)
jl_apply_generic at /Applications/Julia-1.6.app/Contents/Resources/julia/lib/julia/libjulia-internal.1.6.dylib (unknown line)
_print_matrix at ./arrayshow.jl:201
jfptr__print_matrix_19876.clone_1 at /Applications/Julia-1.6.app/Contents/Resources/julia/lib/julia/sys.dylib (unknown line)
jl_apply_generic at /Applications/Julia-1.6.app/Contents/Resources/julia/lib/julia/libjulia-internal.1.6.dylib (unknown line)
do_apply at /Applications/Julia-1.6.app/Contents/Resources/julia/lib/julia/libjulia-internal.1.6.dylib (unknown line)
jl_f__apply_latest at /Applications/Julia-1.6.app/Contents/Resources/julia/lib/julia/libjulia-internal.1.6.dylib (unknown line)
#invokelatest#2 at ./essentials.jl:707 [inlined]
invokelatest at ./essentials.jl:706 [inlined]
print_matrix at ./arrayshow.jl:170 [inlined]
print_matrix at ./arrayshow.jl:170 [inlined]
print_array at ./arrayshow.jl:327 [inlined]
show at ./arrayshow.jl:368
unknown function (ip: 0x16473b078)
jl_apply_generic at /Applications/Julia-1.6.app/Contents/Resources/julia/lib/julia/libjulia-internal.1.6.dylib (unknown line)
#38 at /Users/julia/src/julia/usr/share/julia/stdlib/v1.6/REPL/src/REPL.jl:220
jfptr_YY.38_54434.clone_1 at /Applications/Julia-1.6.app/Contents/Resources/julia/lib/julia/sys.dylib (unknown line)
jl_apply_generic at /Applications/Julia-1.6.app/Contents/Resources/julia/lib/julia/libjulia-internal.1.6.dylib (unknown line)
with_repl_linfo at /Users/julia/src/julia/usr/share/julia/stdlib/v1.6/REPL/src/REPL.jl:462
jl_apply_generic at /Applications/Julia-1.6.app/Contents/Resources/julia/lib/julia/libjulia-internal.1.6.dylib (unknown line)
display at /Users/julia/src/julia/usr/share/julia/stdlib/v1.6/REPL/src/REPL.jl:213
display at /Users/julia/src/julia/usr/share/julia/stdlib/v1.6/REPL/src/REPL.jl:225
jl_apply_generic at /Applications/Julia-1.6.app/Contents/Resources/julia/lib/julia/libjulia-internal.1.6.dylib (unknown line)
display at ./multimedia.jl:328
jl_apply_generic at /Applications/Julia-1.6.app/Contents/Resources/julia/lib/julia/libjulia-internal.1.6.dylib (unknown line)
do_apply at /Applications/Julia-1.6.app/Contents/Resources/julia/lib/julia/libjulia-internal.1.6.dylib (unknown line)
jl_f__apply_latest at /Applications/Julia-1.6.app/Contents/Resources/julia/lib/julia/libjulia-internal.1.6.dylib (unknown line)
#invokelatest#2 at ./essentials.jl:707 [inlined]
invokelatest at ./essentials.jl:706 [inlined]
print_response at /Users/julia/src/julia/usr/share/julia/stdlib/v1.6/REPL/src/REPL.jl:247
#40 at /Users/julia/src/julia/usr/share/julia/stdlib/v1.6/REPL/src/REPL.jl:231
jfptr_YY.40_54549.clone_1 at /Applications/Julia-1.6.app/Contents/Resources/julia/lib/julia/sys.dylib (unknown line)
jl_apply_generic at /Applications/Julia-1.6.app/Contents/Resources/julia/lib/julia/libjulia-internal.1.6.dylib (unknown line)
with_repl_linfo at /Users/julia/src/julia/usr/share/julia/stdlib/v1.6/REPL/src/REPL.jl:462
jl_apply_generic at /Applications/Julia-1.6.app/Contents/Resources/julia/lib/julia/libjulia-internal.1.6.dylib (unknown line)
print_response at /Users/julia/src/julia/usr/share/julia/stdlib/v1.6/REPL/src/REPL.jl:229
do_respond at /Users/julia/src/julia/usr/share/julia/stdlib/v1.6/REPL/src/REPL.jl:798
unknown function (ip: 0x164736c14)
jl_apply_generic at /Applications/Julia-1.6.app/Contents/Resources/julia/lib/julia/libjulia-internal.1.6.dylib (unknown line)
do_apply at /Applications/Julia-1.6.app/Contents/Resources/julia/lib/julia/libjulia-internal.1.6.dylib (unknown line)
jl_f__apply_latest at /Applications/Julia-1.6.app/Contents/Resources/julia/lib/julia/libjulia-internal.1.6.dylib (unknown line)
#invokelatest#2 at ./essentials.jl:707 [inlined]
invokelatest at ./essentials.jl:706 [inlined]
run_interface at /Users/julia/src/julia/usr/share/julia/stdlib/v1.6/REPL/src/LineEdit.jl:2441
jfptr_run_interface_53490.clone_1 at /Applications/Julia-1.6.app/Contents/Resources/julia/lib/julia/sys.dylib (unknown line)
jl_apply_generic at /Applications/Julia-1.6.app/Contents/Resources/julia/lib/julia/libjulia-internal.1.6.dylib (unknown line)
run_frontend at /Users/julia/src/julia/usr/share/julia/stdlib/v1.6/REPL/src/REPL.jl:1126
#44 at ./task.jl:406
jfptr_YY.44_53690.clone_1 at /Applications/Julia-1.6.app/Contents/Resources/julia/lib/julia/sys.dylib (unknown line)
jl_apply_generic at /Applications/Julia-1.6.app/Contents/Resources/julia/lib/julia/libjulia-internal.1.6.dylib (unknown line)
start_task at /Applications/Julia-1.6.app/Contents/Resources/julia/lib/julia/libjulia-internal.1.6.dylib (unknown line)
Allocations: 4752381 (Pool: 4751109; Big: 1272); GC: 5
Illegal instruction: 4

versioninfo()
Julia Version 1.6.0-beta1
Commit b84990e1ac (2021-01-08 12:42 UTC)
Platform Info:
OS: macOS (x86_64-apple-darwin19.6.0)
CPU: Intel(R) Core(TM) i9-9880H CPU @ 2.30GHz
WORD_SIZE: 64
LIBM: libopenlibm
LLVM: libLLVM-11.0.0 (ORCJIT, skylake)
Environment:
JULIA_NUM_THREADS = 4

(@v1.6) pkg> status TypedPolynomials MultivariatePolynomials
Status `~/.julia/environments/v1.6/Project.toml`
[102ac46a] MultivariatePolynomials v0.3.12
[afbbf031] TypedPolynomials v0.2.8

Issue 2:
The following crash showed up in tests, and doesn't happen on 1.7.0-DEV.211 for me, nor on 1.5.

Originally at invenia/NamedDims.jl#152

julia> versioninfo()
Julia Version 1.6.0-beta1
Commit b84990e1ac (2021-01-08 12:42 UTC)
Platform Info:
OS: macOS (x86_64-apple-darwin19.6.0)
CPU: Intel(R) Core(TM) i5-7360U CPU @ 2.30GHz
WORD_SIZE: 64
LIBM: libopenlibm
LLVM: libLLVM-11.0.0 (ORCJIT, skylake)
Environment:
JULIA_NUM_THREADS = 4
JULIA_PKG_SERVER = https://geo.pkg.julialang.org

(jl_Tsdfk7) pkg> st NamedDims
Status `/private/var/folders/d0/hrtbsjqj66qf8zm88ycw9_580000gp/T/jl_Tsdfk7/Project.toml`
[356022a1] NamedDims v0.2.29

julia> using NamedDims

julia> a = [10 20; 31 40];

julia> nda = NamedDimsArray(a, (:x, :y));

julia> hcat(nda) == vcat(nda) # both trivial!
true

julia> for (f, d) in zip((vcat, hcat), (1, 2))
f(nda) # was testing == cat(nda; dims=d)
end

signal (4): Illegal instruction: 4
in expression starting at REPL[6]:1
_zip_iterate_all at ./iterators.jl:361 [inlined]
iterate at ./iterators.jl:351 [inlined]
top-level scope at ./REPL[6]:2
jl_toplevel_eval_flex at /Applications/Julia-1.6.app/Contents/Resources/julia/lib/julia/libjulia-internal.1.dylib (unknown line)
jl_toplevel_eval_flex at /Applications/Julia-1.6.app/Contents/Resources/julia/lib/julia/libjulia-internal.1.dylib (unknown line)
jl_toplevel_eval_flex at /Applications/Julia-1.6.app/Contents/Resources/julia/lib/julia/libjulia-internal.1.dylib (unknown line)
jl_toplevel_eval_flex at /Applications/Julia-1.6.app/Contents/Resources/julia/lib/julia/libjulia-internal.1.dylib (unknown line)
jl_toplevel_eval_in at /Applications/Julia-1.6.app/Contents/Resources/julia/lib/julia/libjulia-internal.1.dylib (unknown line)
eval at ./boot.jl:360
jl_apply_generic at /Applications/Julia-1.6.app/Contents/Resources/julia/lib/julia/libjulia-internal.1.dylib (unknown line)
eval_user_input at /Users/julia/src/julia/usr/share/julia/stdlib/v1.6/REPL/src/REPL.jl:139
repl_backend_loop at /Users/julia/src/julia/usr/share/julia/stdlib/v1.6/REPL/src/REPL.jl:200
start_repl_backend at /Users/julia/src/julia/usr/share/julia/stdlib/v1.6/REPL/src/REPL.jl:185
#run_repl#42 at /Users/julia/src/julia/usr/share/julia/stdlib/v1.6/REPL/src/REPL.jl:317