Fix cases of string formatting with non string literals (#3304)

The logger used in `goalc` tries to print an already-formatted string
`message` using `fmt::print(message);` Usually this doesn't cause
problems, but if you try to print, for example, an exception that has
special characters (notably `{`) it will try to do another round of
formatting/replacements, despite not having any args to replace with,
which ends up throwing another exception. This is why errors when
parsing custom level JSON cause the REPL to exit.

I've hopefully identified all the various instances of this across the
codebase

decompiler/ObjectFile/ObjectFileDB_IR2.cpp

@@ -802,7 +802,7 @@ void ObjectFileDB::ir2_insert_lets(int seg, ObjectFileData& data) {
             "Error while inserting lets: {}. Make sure that the return type is not "
             "none if something is actually returned.",
             e.what());
-        lg::warn(err);
+        lg::warn("{}", err);
         func.warnings.error(err);
       }
     }