More state reset fixes.

Author: microbit-matt-hillsdon

src/board/data-logging.ts

@@ -138,6 +138,8 @@ export class DataLogging {
   delete() {
     this.resetNonFlashStateExceptTimestamp();
     this.headings = [];
+    this.timestampOnLastEndRow = undefined;
+
     this.size = 0;
     if (this.logFull) {
       this.logFull = false;
@@ -156,7 +158,6 @@ export class DataLogging {
     // headings are considered flash state as MicroBitLog reparses them from flash
     this.mirroring = false;
     this.headingsChanged = false;
-    this.timestampOnLastEndRow = undefined;
     this.row = undefined;
   }
 }