Invalid escape sequences in strings and characters are not properly reported

[PeterGriffinSr]

Describe the bug
When using invalid escape sequences inside string or character literals, Zura Lang either fails to report an error properly or crashes.

To reproduce
Steps to reproduce the behavior:

1. Create two separate files strings.zu and chars.zu with the following contents:

const main := fn () int! {
    have x: str  = "Hello\xZ";
    return 0;
};

const main := fn () int! {
    have x: char  = '\q';
    return 0;
};

2. Run the command:

./debug/zura build zura_files/main.zu

3. Observe the behavior:

• No error is reported for the invalid escape sequence in the string literal "Hello\xZ".
• The invalid escape in the character literal '\q' produces an error message, but then the compiler crashes with a segmentation fault.

Expected behavior

• The compiler should report invalid escape sequence errors for both string and character literals.
• The compiler should not crash when encountering invalid characters.
• Error messages should point to the exact location in the source file. Example:

chars.zu:2:23: Lexer error: Invalid escape sequence in character literal '\q'
strings.zu:2:18: Lexer error: Invalid escape sequence in string literal "Hello\xZ"

screenshots

Additional context

• Zura Lang version: v0.1.46
• This issue affects any invalid escape sequences (\x with non-hex digits, unsupported letters, etc.) in both strings and character literals.

[TheSovietPancakes]

Thank you for creating the issue. I know this has been an issue in the compiler basically since strings were implemented, and I have a potential fix in mind.

The reasons for these errors is that the contents of all characters between the quotation marks is handed literally to the assembler to then decode the escape sequences there instead of implementing something in Zura. So, if you have "Hello, world!\n\c" in Zura, that entire thing gets taken to gcc to parse, which incorrectly handles invalid sequences. Therefore, the lack of error reporting and segfault is likely the assembler (gcc)'s fault, but a fix in the Zura compiler may be coming soon.

Thank you for taking the time to fill out such a detailed report. I will look into potential ways to fix the issue soon.