Rollup merge of #140700 - Kivooeo:new-fix-six, r=davidtwco,fmease

Don't crash on error codes passed to `--explain` which exceed our internal limit of 9999

removed panic in case where we do `--explain > 9999` and added check for it

now error looks like this instead of ICE
```
$ rustc.exe --explain E10000
error: E10000 is not a valid error code
```
fixes #140647
r? `@fmease`

Author: GuillaumeGomez