fix: prevent stale errors

src/connection.ts

@@ -3176,6 +3176,7 @@ class Connection extends EventEmitter {
       request.rowCount! = 0;
       request.rows! = [];
       request.rst! = [];
+      request.error = undefined;
 
       const onCancel = () => {
         payloadStream.unpipe(message);

test/integration/prepare-execute-statements-test.ts

@@ -156,6 +156,87 @@ describe('Prepare Execute Statement', function() {
     });
   });
 
+  it('should not persist error state between executions of prepared statement (GH#1712)', function(done) {
+    const config = getConfig();
+
+    const connection = new Connection(config);
+    if (process.env.TEDIOUS_DEBUG) {
+      connection.on('debug', console.log);
+    }
+
+    // Prepare a statement that can cause a divide by zero error depending on the parameter
+    const request = new Request('select 1 / @divisor as result', function() {});
+    request.addParameter('divisor', TYPES.Int);
+
+    let executionCount = 0;
+    const results: (number | null)[] = [];
+    const errors: (Error | undefined)[] = [];
+
+    request.on('row', function(columns) {
+      results.push(columns[0].value);
+    });
+
+    request.on('prepared', function() {
+      assert.ok(request.handle);
+
+      // First execution: should succeed with divisor = 1
+      request.once('requestCompleted', function() {
+        executionCount++;
+        errors.push(request.error);
+
+        // Second execution: should fail with divisor = 0 (divide by zero)
+        request.once('requestCompleted', function() {
+          executionCount++;
+          errors.push(request.error);
+
+          // Third execution: should succeed with divisor = 2
+          // Before the fix, this would report the error from the second execution
+          request.once('requestCompleted', function() {
+            executionCount++;
+            errors.push(request.error);
+
+            // Unprepare and close
+            connection.unprepare(request);
+            connection.close();
+          });
+
+          connection.execute(request, { divisor: 2 });
+        });
+
+        connection.execute(request, { divisor: 0 });
+      });
+
+      connection.execute(request, { divisor: 1 });
+    });
+
+    connection.connect(function(err) {
+      if (err) {
+        return done(err);
+      }
+
+      connection.prepare(request);
+    });
+
+    connection.on('end', function() {
+      // Verify the behavior
+      assert.strictEqual(executionCount, 3, 'Should have completed 3 executions');
+
+      // First execution succeeded
+      assert.isUndefined(errors[0], 'First execution should have no error');
+      assert.strictEqual(results[0], 1, 'First execution should return 1');
+
+      // Second execution failed with divide by zero
+      assert.isDefined(errors[1], 'Second execution should have an error');
+      assert.include(errors[1]!.message, 'Divide by zero', 'Error should be divide by zero');
+
+      // Third execution succeeded - this is the key assertion for GH#1712
+      assert.isUndefined(errors[2], 'Third execution should have no error (error state should be cleared)');
+      assert.strictEqual(results[1], 0, 'Third execution should return 0 (1/2 truncated to int)');
+
+      done();
+    });
+  });
+
   it('should test unprepare', function(done) {
     const config = getConfig();
     const request = new Request('select 3', function(err) {