T6587: Raise an error when trying to get information about network in…

…terfaces that don't exist

src/op_mode/interfaces.py

@@ -450,7 +450,13 @@ def show(raw: bool, intf_name: typing.Optional[str],
                     vif: bool, vrrp: bool):
     data = _get_raw_data(intf_name, intf_type, vif, vrrp)
     if raw:
-        return data
+        if intf_name is not None and len(data) <= 1:
+            try:
+                return data[0]
+            except IndexError:
+                raise vyos.opmode.UnconfiguredObject(f"Interface {intf_name} does not exist")
+        else:
+            return data
     return _format_show_data(data)
 
 def show_summary(raw: bool, intf_name: typing.Optional[str],
@@ -459,7 +465,10 @@ def show_summary(raw: bool, intf_name: typing.Optional[str],
     data = _get_summary_data(intf_name, intf_type, vif, vrrp)
     if raw:
         if intf_name is not None and len(data) <= 1:
-            return data[0] if data else {}
+            try:
+                return data[0]
+            except IndexError:
+                raise vyos.opmode.UnconfiguredObject(f"Interface {intf_name} does not exist")
         else:
             return data
     return _format_show_summary(data)