Change: Improve error output in case of unix socket connection issues (…

…#835)

Add the causing exception message to the raised error if connecting to
the unix socket fails. This will allow for better debugging of the
cause.

gvm/connections.py

@@ -503,8 +503,10 @@ def connect(self) -> None:
             self._socket.connect(self.path)
         except FileNotFoundError:
             raise GvmError(f"Socket {self.path} does not exist") from None
-        except ConnectionError:
-            raise GvmError(f"Could not connect to socket {self.path}") from None
+        except ConnectionError as e:
+            raise GvmError(
+                f"Could not connect to socket {self.path}. Error was {e}"
+            ) from None
 
 
 class DebugConnection: