org-table.el: Fix a bug of leaving the inserted TBLFM line

* org-table.el (org-calc-current-TBLFM): Ensure to remove the
currently inserted TBLFM line, when calling `org-table-recalculate'
returns an error and the processing stops.

* testing/lisp/test-org-table.el: Add test.

When you hit =C-c C-c= at the line of "#+TBLFM: $2=$1*2::$2=$1**2" in

    | 1 |   |
    | 2 |   |
    #+TBLFM: $2=$1*1
    #+TBLFM: $2=$1*2::$2=$1**2

you got:

    | 1 |   |
    | 2 |   |
    #+TBLFM: $2=$1*2::$2=$1**2
    #+TBLFM: $2=$1*1
    #+TBLFM: $2=$1*2::$2=$1**2

with the error message of:

    user-error: Double definition `$2=' in TBLFM line, please fix by hand

In this case, you expected:

    | 1 |   |
    | 2 |   |
    #+TBLFM: $2=$1*1
    #+TBLFM: $2=$1*2::$2=$1**2

lisp/org-table.el

@@ -3190,10 +3190,11 @@ with the prefix ARG."
       (beginning-of-line 0)		; move to the inserted line
       (skip-chars-backward " \r\n\t")
       (if (org-at-table-p)
-	  (org-call-with-arg 'org-table-recalculate (or arg t)))
+	  (unwind-protect
+	      (org-call-with-arg 'org-table-recalculate (or arg t))
 
-      ;; Delete the formula inserted temporarily
-      (delete-region s e))))
+	    ;; delete the formula inserted temporarily
+	    (delete-region s e))))))
 
 (defun org-TBLFM-begin ()
   "Find the beginning of the TBLFM lines and return its position.

testing/lisp/test-org-table.el

@@ -929,6 +929,31 @@ reference (with row).  Format specifier N."
       (should (string= got
 		       expect)))))
 
+(ert-deftest test-org-table/org-calc-current-TBLFM-when-stop-because-of-error ()
+  "org-calc-current-TBLFM should preserve the input as it was."
+  (org-test-with-temp-text-in-file
+      "
+| 1 | 1 |
+| 2 | 2 |
+#+TBLFM: $2=$1*1
+#+TBLFM: $2=$1*2::$2=$1*2
+#+TBLFM: $2=$1*3
+"
+    (let ((expect "
+| 1 | 1 |
+| 2 | 2 |
+#+TBLFM: $2=$1*1
+#+TBLFM: $2=$1*2::$2=$1*2
+#+TBLFM: $2=$1*3
+"))
+      (goto-char (point-min))
+      (forward-line 4)
+      (should-error (org-calc-current-TBLFM))
+      (setq got (buffer-string))
+      (message "%s" got)
+      (should (string= got
+		       expect)))))
+
 (provide 'test-org-table)
 
 ;;; test-org-table.el ends here