fix(plot/image): monitors are now validated with current bec session

bec_widgets/utils/entry_validator.py

@@ -3,6 +3,15 @@ class EntryValidator:
         self.devices = devices
 
     def validate_signal(self, name: str, entry: str = None) -> str:
+        """
+        Validate a signal entry for a given device. If the entry is not provided, the first signal entry will be used from the device hints.
+        Args:
+            name(str): Device name
+            entry(str): Signal entry
+
+        Returns:
+            str: Signal entry
+        """
         if name not in self.devices:
             raise ValueError(f"Device '{name}' not found in current BEC session")
 
@@ -15,3 +24,17 @@ class EntryValidator:
             raise ValueError(f"Entry '{entry}' not found in device '{name}' signals")
 
         return entry
+
+    def validate_monitor(self, monitor: str) -> str:
+        """
+        Validate a monitor entry for a given device.
+        Args:
+            monitor(str): Monitor entry
+
+        Returns:
+            str: Monitor entry
+        """
+        if monitor not in self.devices:
+            raise ValueError(f"Device '{monitor}' not found in current BEC session")
+
+        return monitor