common: refine subgraph query result shape validation

packages/indexer-common/src/subgraphs.ts

@@ -446,14 +446,22 @@ export class SubgraphFreshnessChecker {
       return subgraphQueryResult
     }
 
-    const latestIndexedBlock = subgraphQueryResult?.data?._meta?.block?.number
-    if (!latestIndexedBlock) {
-      const errorMsg = `Failed to infer block number for ${this.subgraphName} query`
-      this.logger.error(errorMsg, { query: print(updatedQuery) })
-      // Check for unexpected missing block data as a precaution.
+    // Check for missing block metadata
+    const queryShapeError = this.checkMalformedQueryResult(subgraphQueryResult)
+    if (queryShapeError) {
+      const errorMsg = `Failed to infer block number for ${this.subgraphName} query: ${queryShapeError}`
+      this.logger.error(errorMsg, {
+        query: print(updatedQuery),
+        subgraph: this.subgraphName,
+        error: queryShapeError,
+        subgraphQueryResult,
+      })
       throw new Error(errorMsg)
     }
 
+    // At this point we have validated that this value exists and is numeric.
+    const latestIndexedBlock: number = subgraphQueryResult.data._meta.block.number
+
     // Check subgraph freshness
     const blockDistance = latestNetworkBlock - latestIndexedBlock
     const logInfo = {
@@ -485,4 +493,27 @@ export class SubgraphFreshnessChecker {
     }
     return subgraphQueryResult
   }
+
+  // Checks if the query result has the expecte
+  // eslint-disable-next-line @typescript-eslint/no-explicit-any
+  checkMalformedQueryResult(subgraphQueryResult: any): string | undefined {
+    if (!subgraphQueryResult) {
+      return 'Subgraph query result is null or undefined'
+    }
+    if (!subgraphQueryResult.data) {
+      return 'Subgraph query data is null or undefined'
+    }
+    if (!subgraphQueryResult.data._meta) {
+      return 'Query metadata is null or undefined'
+    }
+    if (!subgraphQueryResult.data._meta.block) {
+      return 'Block metadata is null or undefined'
+    }
+    if (
+      !subgraphQueryResult.data._meta.block.number &&
+      typeof subgraphQueryResult.data._meta.block.number === 'number'
+    ) {
+      return 'Block number is null or undefined'
+    }
+  }
 }