fix: Improve handling of missing data fields in MikroTik BGP parser

- Update MikroTik parser to return -1 for unavailable age data instead of "0"
- Change age property return type from string to int for consistency
- Enhance frontend Age component to display "N/A" when age is -1
- Improve MonoField component to handle empty/undefined values gracefully
- Add appropriate tooltips and styling for missing data indicators

This addresses the issue where MikroTik devices don't provide route age
and source RID information, ensuring the UI displays user-friendly
indicators instead of potentially misleading placeholder values.

hyperglass/models/parsing/mikrotik.py

@@ -76,9 +76,9 @@ class MikrotikRouteEntry(MikrotikBase):
         return self.gateway
 
     @property
-    def age(self) -> str:
-        # MikroTik output does not provide route age, returning 0 as a placeholder.
-        return "0"
+    def age(self) -> int:
+        # MikroTik output does not provide route age, returning -1 to indicate unavailable.
+        return -1
 
     @property
     def weight(self) -> int:
@@ -102,6 +102,7 @@ class MikrotikRouteEntry(MikrotikBase):
 
     @property
     def source_rid(self) -> str:
+        # MikroTik output does not provide source RID, returning empty string.
         return ""
 
     @property

hyperglass/ui/components/output/fields.tsx

@@ -50,6 +50,16 @@ dayjs.extend(utcPlugin);
 
 export const MonoField = (props: MonoFieldProps): JSX.Element => {
   const { v, ...rest } = props;
+  
+  // Handle empty or undefined values
+  if (!v || (typeof v === 'string' && v.trim() === '')) {
+    return (
+      <Text as="span" fontSize="sm" fontFamily="mono" color="gray.500" {...rest}>
+        N/A
+      </Text>
+    );
+  }
+  
   return (
     <Text as="span" fontSize="sm" fontFamily="mono" {...rest}>
       {v}
@@ -74,6 +84,18 @@ export const Active = (props: ActiveProps): JSX.Element => {
 
 export const Age = (props: AgeProps): JSX.Element => {
   const { inSeconds, ...rest } = props;
+  
+  // Handle case where age is not available (e.g., MikroTik)
+  if (inSeconds === -1) {
+    return (
+      <Tooltip hasArrow label="Age information not available" placement="right">
+        <Text fontSize="sm" color="gray.500" {...rest}>
+          N/A
+        </Text>
+      </Tooltip>
+    );
+  }
+  
   const now = dayjs.utc();
   const then = now.subtract(inSeconds, 'second');
   return (