Re-enable users of {expr,nondet}_initializer to do their own error reporting

[tautschnig]

With d5535a9 {expr,nondet}_initializer would
fail an invariant when an expression of the chosen type could not be generated.
As user input code can reasonably trigger this case (see included regression
test), the caller should be able to do error handling as appropriate in a given
context.

• Each commit message has a non-empty body, explaining why the change was made.
• My contribution is formatted in line with CODING_STANDARD.md.
• Methods or procedures I have added are documented, following the guidelines provided in CODING_STANDARD.md.
• Regression or unit tests are included, or existing tests cover the modified code (in this case I have detailed which ones those are in the commit message).
• [n/a] My commit message includes data points confirming performance improvements (if claimed).
• My PR is restricted to a single feature or bugfix.
• [n/a] White-space or formatting changes outside the feature-related changed lines are in commits of their own.

[allredj]

This PR failed Diffblue compatibility checks (cbmc commit: eaf1402).
Build URL: https://travis-ci.com/diffblue/test-gen/builds/86285654
Status will be re-evaluated on next push.
Please contact @peterschrammel, @thk123, or @allredj for support.

Common spurious failures:

• the cbmc commit has disappeared in the mean time (e.g. in a force-push)
• the author is not in the list of contributors (e.g. first-time contributors).

[thk123]

Creating a bump for this now.

[thk123]

Reviewed java_bytecode changes but I don't really have much visibility of what this change is about - only looking at it since it failed the bump

[thk123]

TG bump: https://github.com/diffblue/test-gen/pull/2331

[thk123]

I have a working TG bump 👍

[allredj]

This PR failed Diffblue compatibility checks (cbmc commit: ac26fe2).
Build URL: https://travis-ci.com/diffblue/test-gen/builds/87126628
Status will be re-evaluated on next push.
Please contact @peterschrammel, @thk123, or @allredj for support.

Common spurious failures:

• the cbmc commit has disappeared in the mean time (e.g. in a force-push)
• the author is not in the list of contributors (e.g. first-time contributors).

[allredj]

This PR failed Diffblue compatibility checks (cbmc commit: b2db7ea).
Build URL: https://travis-ci.com/diffblue/test-gen/builds/88747686
Status will be re-evaluated on next push.
Please contact @peterschrammel, @thk123, or @allredj for support.

Common spurious failures:

• the cbmc commit has disappeared in the mean time (e.g. in a force-push)
• the author is not in the list of contributors (e.g. first-time contributors).

The incompatibility may have been introduced by an earlier PR. In that case merging this
PR should be avoided unless it fixes the current incompatibility.

[allredj]

This PR failed Diffblue compatibility checks (cbmc commit: c2dbb57).
Build URL: https://travis-ci.com/diffblue/test-gen/builds/88785946
Status will be re-evaluated on next push.
Please contact @peterschrammel, @thk123, or @allredj for support.

Common spurious failures:

• the cbmc commit has disappeared in the mean time (e.g. in a force-push)
• the author is not in the list of contributors (e.g. first-time contributors).

The incompatibility may have been introduced by an earlier PR. In that case merging this
PR should be avoided unless it fixes the current incompatibility.

[tautschnig]

@peterschrammel @thk123 @allredj Could you please let me know whether the TG failure is a genuine one? There was a past bump (see above), but that's 25 days ago...

[thk123]

The bump did require code changes so I'm not surprised Joel-bot is unhappy - I see Peter has just rebased it but I suppose once that passes this will be good to go

[tautschnig]

@thk123 @peterschrammel thanks a lot for the immediate support!

[peterschrammel]

Unfortunately, it's not passing.

[tautschnig]

Unfortunately, it's not passing.

Please let me know if there is anything I can do to help!

[peterschrammel]

This PR is fine. It's due to an earlier merge causing the failure. All subsequent PRs based on cbmc/develop:HEAD are then reported as conflicting.

[tautschnig]

This PR is fine. It's due to an earlier merge causing the failure. [...]

I guess I should still wait before merging this PR to avoid even more chaos on the TG side?