fixed lexing expression ending with spaces
bug #9621 [ExpressionLanguage] fixed lexing expression ending with spaces (fabpot)

This PR was submitted for the master branch but it was merged into the 2.4 branch instead (closes #9621).

Discussion
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[ExpressionLanguage] fixed lexing expression ending with spaces

| Q             | A
| ------------- | ---
| Bug fix?      | yes
| New feature?  | no
| BC breaks?    | no
| Deprecations? | no
| Tests pass?   | yes
| Fixed tickets | #9606, #9615
| License       | MIT
| Doc PR        |

Alternative fix for #9615

Commits
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d8f61c4 [ExpressionLanguage] fixed lexing expression ending with spaces