Small fixes and bigger library

src/bedit_simulation/openmodelica.py

@@ -24,6 +24,14 @@ class ProcessResult:
     stdout: str
     stderr: str
 
+    def diagnostics(self) -> str:
+        sections = []
+        if self.stdout.strip():
+            sections.append(f"OpenModelica output:\n{self.stdout.strip()}")
+        if self.stderr.strip():
+            sections.append(f"OpenModelica errors:\n{self.stderr.strip()}")
+        return "\n\n".join(sections)
+
 
 class OpenModelicaError(RuntimeError):
     """Raised when OMC cannot start or reports a failure."""
@@ -80,7 +88,7 @@ class OpenModelicaRunner:
                 f"OpenModelica timed out after {error.timeout} seconds"
             ) from error
         if result.return_code != 0:
-            details = result.stderr.strip() or result.stdout.strip()
+            details = result.diagnostics()
             suffix = f": {details}" if details else ""
             raise OpenModelicaError(
                 f"OpenModelica exited with status {result.return_code}{suffix}"
@@ -128,7 +136,7 @@ class OpenModelicaRunner:
                 continue
         result = ProcessResult(command=tuple(command), return_code=process.returncode, stdout=stdout, stderr=stderr)
         if result.return_code != 0:
-            details = result.stderr.strip() or result.stdout.strip()
+            details = result.diagnostics()
             suffix = f": {details}" if details else ""
             raise OpenModelicaError(f"simulation exited with status {result.return_code}{suffix}")
         return result