handle slash added by maven on windows (#691)

* Using a __post_init__ function for the dataclass generated init to
  take care of this for us.

Signed-off-by: Shawn Hurley <shawn@hurley.page>

kai/reactive_codeplanner/task_runner/compiler/maven_validator.py

@@ -2,6 +2,7 @@
 
 import re
 import subprocess  # trunk-ignore(bandit/B404)
+import sys
 from abc import ABC, abstractmethod
 from dataclasses import dataclass, field
 from functools import cached_property
@@ -91,6 +92,12 @@ def from_match(
     def compiler_error_message(self) -> str:
         return self.message
 
+    def __post_init__(self) -> None:
+        if sys.platform == "win32":
+            regex = re.compile(r"^/[a-zA-Z]:")
+            if re.match(regex, self.file):
+                self.file = self.file.removeprefix("/")
+
 
 class CollapsedMavenCompilerError(ABC, MavenCompilerError):
     lines: list[int] | None = None
@@ -586,14 +593,15 @@ def catchall(output: str) -> OtherError:
     file_path_pattern = re.compile(r"(/[^:\s]+)")
     file_path_matches = file_path_pattern.findall(output)
     file_path = file_path_matches[0] if file_path_matches else "unknown file"
-    return OtherError(
+    error = OtherError(
         file=file_path,
         line=-1,
         column=-1,
         message="Unknown error occurred during Maven build.",
         details=[output],
         parse_lines=output,
     )
+    return error
 
 
 def deduplicate_errors(errors: list[MavenCompilerError]) -> list[MavenCompilerError]: