Fix (not) handling exceptions when creating processes

CHANGELOG.rst

@@ -24,6 +24,12 @@ Changed
   ``timeout`` parameter is still accepted, but will add a
   ``DeprecationWarning`` and will be removed in future versions.
 
+Fixed
+^^^^^
+
+- Fix problem where some exceptions when creating processes where hidden and
+  would then cause errors where the ``proc`` variable did not exist.
+
 0.9.0_ - 2023-04-04
 -------------------
 

src/minizinc/helpers.py

@@ -57,8 +57,10 @@ def check_result(
 
     return True
 
+
 class TimeoutError(Exception):
     """Exception raised for timeout errors (UNKNOWN status) when checking solutions"""
+
     pass
 
 
@@ -102,7 +104,9 @@ def check_solution(
     check = instance.solve(time_limit=time_limit)
 
     if check.status is minizinc.Status.UNKNOWN:
-        raise TimeoutError(f"Solution checking failed because the checker exceeded the allotted time limit of {time_limit}")
+        raise TimeoutError(
+            f"Solution checking failed because the checker exceeded the allotted time limit of {time_limit}"
+        )
     elif status == check.status:
         return True
     return check.status in [

src/minizinc/instance.py

@@ -288,7 +288,10 @@ async def solutions(
         """
         # rewrite deprecated option `timeout`
         if timeout is not None and time_limit is None:
-            warnings.warn("The usage of the `timeout` parameter is deprecated, please use the `time_limit` parameter instead.", DeprecationWarning)
+            warnings.warn(
+                "The usage of the `timeout` parameter is deprecated, please use the `time_limit` parameter instead.",
+                DeprecationWarning,
+            )
             time_limit = timeout
 
         method = self.method  # Ensure self.analyse() has been executed
@@ -381,9 +384,9 @@ async def solutions(
             # Whether the status has changed since the last `yield`
             status_changed = False
 
+            # Run the MiniZinc process
+            proc = await self._driver._create_process(cmd, solver=solver)
             try:
-                # Run the MiniZinc process
-                proc = await self._driver._create_process(cmd, solver=solver)
                 assert isinstance(proc.stderr, asyncio.StreamReader)
                 assert isinstance(proc.stdout, asyncio.StreamReader)
 
@@ -693,7 +696,10 @@ def flat(
         """
         # rewrite deprecated option `timeout`
         if timeout is not None and time_limit is None:
-            warnings.warn("The usage of the `timeout` parameter is deprecated, please use the `time_limit` parameter instead.", DeprecationWarning)
+            warnings.warn(
+                "The usage of the `timeout` parameter is deprecated, please use the `time_limit` parameter instead.",
+                DeprecationWarning,
+            )
             time_limit = timeout
 
         cmd: List[Any] = ["--compile", "--statistics"]