ignore migration events while parsing calls (#319)

* ignore migration events while parsing calls

* add comment

common/changes/@subsquid/substrate-data/master_2024-07-23-12-11.json

@@ -0,0 +1,10 @@
+{
+  "changes": [
+    {
+      "packageName": "@subsquid/substrate-data",
+      "comment": "ignore events from `Migrations` pallet while parsing calls",
+      "type": "patch"
+    }
+  ],
+  "packageName": "@subsquid/substrate-data"
+}

substrate/substrate-data/src/parsing/call/parser.ts

@@ -326,12 +326,34 @@ export class CallParser {
         while (this.eventPos >= 0) {
             let event = this.events[this.eventPos]
             if (event.phase === 'ApplyExtrinsic') {
-                if (event.extrinsicIndex !== this.extrinsic.index) return
+                if (event.extrinsicIndex !== this.extrinsic.index) {
+                    if (event.name.startsWith('Migrations.')) {
+                        let index = assertNotNull(event.extrinsicIndex)
+                        // Besides `Migrations.*` events there can be more parachain-defined events,
+                        // so we skip all events related to the "phantom" extrinsic.
+                        this.skipExtrinsicEvents(index)
+                        continue
+                    } else {
+                        return
+                    }
+                }
+
                 this.eventPos -= 1
                 return event
             } else {
                 this.eventPos -= 1
             }
         }
     }
+
+    private skipExtrinsicEvents(extrinsicIndex: number) {
+        while (true) {
+            let event = this.events[this.eventPos]
+            if (event.extrinsicIndex == extrinsicIndex) {
+                this.eventPos -= 1
+            } else {
+                break
+            }
+        }
+    }
 }