# Buggy code
def as_create_delta(
    self,
    schema: s_schema.Schema,
    *,
    view_name: Optional[s_name.QualName] = None,
    attrs: Optional[Dict[str, Any]] = None,
) -> sd.CommandGroup:
    ca: Union[CreateArray, CreateArrayExprAlias]
    cmd = sd.CommandGroup()
    type_id = self.get_id(schema)
    if view_name is None:
        ca = CreateArray(
            classname=self.get_name(schema),
            if_not_exists=True,
        )
    else:
        ca = CreateArrayExprAlias(
            classname=view_name,
        )

    el = self.subtype
    if (
        isinstance(el, CollectionTypeShell)
        and schema.get_by_id(el.get_id(schema), None) is None
    ):
        cmd.add(el.as_create_delta(schema))

    ca.set_attribute_value("id", type_id)
    ca.set_attribute_value("name", ca.classname)
    ca.set_attribute_value("element_type", el)
    ca.set_attribute_value("is_persistent", True)
    ca.set_attribute_value("dimensions", self.typemods[0])

    if attrs:
        for k, v in attrs.items():
            ca.set_attribute_value(k, v)

    cmd.add(ca)

    return cmd


# Traceback (AttributeError)
ERROR: InternalServerError: 'UnionType' object has no attribute 'get_name'
Hint: This is most likely a bug in EdgeDB. Please consider opening an issue ticket at https://github.com/edgedb/edgedb/issues/new?template=bug_report.md
Server traceback:
Traceback (most recent call last):
File "/usr/lib/x86_64-linux-gnu/edgedb-server-1-alpha6/lib/python3.8/site-packages/edb/server/procpool/worker.py", line 75, in worker
res = await meth(*args)
File "/usr/lib/x86_64-linux-gnu/edgedb-server-1-alpha6/lib/python3.8/site-packages/edb/server/compiler/compiler.py", line 1808, in compile_eql_tokens
return self._compile(ctx=ctx, tokens=eql_tokens)
File "/usr/lib/x86_64-linux-gnu/edgedb-server-1-alpha6/lib/python3.8/site-packages/edb/server/compiler/compiler.py", line 1442, in _compile
comp: dbstate.BaseQuery = self._compile_dispatch_ql(ctx, stmt)
File "/usr/lib/x86_64-linux-gnu/edgedb-server-1-alpha6/lib/python3.8/site-packages/edb/server/compiler/compiler.py", line 1365, in _compile_dispatch_ql
return self._compile_ql_migration(ctx, ql)
File "/usr/lib/x86_64-linux-gnu/edgedb-server-1-alpha6/lib/python3.8/site-packages/edb/server/compiler/compiler.py", line 794, in _compile_ql_migration
target_schema = s_ddl.apply_sdl(
File "/usr/lib/x86_64-linux-gnu/edgedb-server-1-alpha6/lib/python3.8/site-packages/edb/schema/ddl.py", line 371, in apply_sdl
ddl_stmts = s_decl.sdl_to_ddl(current_schema, documents)
File "/usr/lib/x86_64-linux-gnu/edgedb-server-1-alpha6/lib/python3.8/site-packages/edb/edgeql/declarative.py", line 230, in sdl_to_ddl
trace_dependencies(decl_ast, ctx=ctx)
File "/usr/lib/x86_64-linux-gnu/edgedb-server-1-alpha6/lib/python3.8/functools.py", line 875, in wrapper
return dispatch(args[0].__class__)(*args, **kw)
File "/usr/lib/x86_64-linux-gnu/edgedb-server-1-alpha6/lib/python3.8/site-packages/edb/edgeql/declarative.py", line 499, in trace_default
_register_item(node, ctx=ctx)
File "/usr/lib/x86_64-linux-gnu/edgedb-server-1-alpha6/lib/python3.8/site-packages/edb/edgeql/declarative.py", line 623, in _register_item
trace_dependencies(cmd, ctx=ctx)
File "/usr/lib/x86_64-linux-gnu/edgedb-server-1-alpha6/lib/python3.8/functools.py", line 875, in wrapper
return dispatch(args[0].__class__)(*args, **kw)
File "/usr/lib/x86_64-linux-gnu/edgedb-server-1-alpha6/lib/python3.8/site-packages/edb/edgeql/declarative.py", line 443, in trace_ConcretePointer
_register_item(
File "/usr/lib/x86_64-linux-gnu/edgedb-server-1-alpha6/lib/python3.8/site-packages/edb/edgeql/declarative.py", line 638, in _register_item
tdeps = qltracer.trace_refs(
File "/usr/lib/x86_64-linux-gnu/edgedb-server-1-alpha6/lib/python3.8/site-packages/edb/edgeql/tracer.py", line 162, in trace_refs
trace(qltree, ctx=ctx)
File "/usr/lib/x86_64-linux-gnu/edgedb-server-1-alpha6/lib/python3.8/functools.py", line 875, in wrapper
return dispatch(args[0].__class__)(*args, **kw)
File "/usr/lib/x86_64-linux-gnu/edgedb-server-1-alpha6/lib/python3.8/site-packages/edb/edgeql/tracer.py", line 653, in trace_Select
ctx.path_prefix = tip.get_name(ctx.schema)
AttributeError: 'UnionType' object has no attribute 'get_name'

# Fixed code
def as_create_delta(
    self,
    schema: s_schema.Schema,
    *,
    view_name: Optional[s_name.QualName] = None,
    attrs: Optional[Dict[str, Any]] = None,
) -> sd.CommandGroup:
    ca: Union[CreateArray, CreateArrayExprAlias]
    cmd = sd.CommandGroup()
    if view_name is None:
        ca = CreateArray(
            classname=self.get_name(schema),
            if_not_exists=True,
        )
        ca.set_attribute_value("id", self.get_id(schema))
    else:
        ca = CreateArrayExprAlias(
            classname=view_name,
        )

    el = self.subtype
    if (
        isinstance(el, CollectionTypeShell)
        and schema.get_by_id(el.get_id(schema), None) is None
    ):
        cmd.add(el.as_create_delta(schema))

    ca.set_attribute_value("name", ca.classname)
    ca.set_attribute_value("element_type", el)
    ca.set_attribute_value("is_persistent", True)
    ca.set_attribute_value("dimensions", self.typemods[0])

    if attrs:
        for k, v in attrs.items():
            ca.set_attribute_value(k, v)

    cmd.add(ca)

    return cmd