Fix(EditInstructionDialog): Silence console errors from text preview

[Keryer]

Your checklist for this pull request

• I've read the guidelines for contributing to this repository
• I made sure to follow the project's coding style
• I've updated the documentation with the relevant information (if needed)

Detailed description

This change resolves Issue #2551, where errors from Rizin were printed to the console when typing invalid instructions in the "Edit Instruction" dialog.

Problem:
When a user entered non-assemblable code, Core()->assemble() would fail. This failure not only caused Rizin to print error messages to the console but could also lead to unhandled exceptions, potentially crashing Cutter.

Fix:
This modification wraps the Core()->assemble(input) call within a try-catch block. By catching the std::exception that Core()->assemble() might throw:

• We successfully prevent the associated error messages, which resulted from these exceptions, from being printed to the console.
• We handle the failure case by setting data to an empty QByteArray.

Test plan (required)
The following is an example of an unexpected console error:

After modification, the console no longer reports an error during the modification of instructions:

Closing issues
closes #2551

[karliss]

Please retest your changes. I have no idea how you managed to produce the second GIF, but the changes you made should have no effect and in my testing they didn't.

[Keryer]

Please retest your changes. I have no idea how you managed to produce the second GIF, but the changes you made should have no effect and in my testing they didn't.

Could you please tell me about your test environment? I will refer to it for further testing.