patch 8.2.0331: internal error when using test_void() and test_unknown()

Problem:    Internal error when using test_void() and test_unknown().
            (Dominique Pelle)
Solution:   Give a normal error.

src/evalfunc.c

@@ -1890,7 +1890,10 @@ f_empty(typval_T *argvars, typval_T *rettv)
 #endif
 	case VAR_UNKNOWN:
 	case VAR_VOID:
-	    internal_error("f_empty(UNKNOWN)");
+	    // Let's not use internal_error() here, otherwise
+	    // empty(test_unknown()) with ABORT_ON_INTERNAL_ERROR defined makes
+	    // Vim abort.
+	    semsg(_(e_intern2), "f_empty(UNKNOWN)");
 	    n = TRUE;
 	    break;
     }
@@ -8275,7 +8278,10 @@ f_type(typval_T *argvars, typval_T *rettv)
 	case VAR_BLOB:    n = VAR_TYPE_BLOB; break;
 	case VAR_UNKNOWN:
 	case VAR_VOID:
-	     internal_error("f_type(UNKNOWN)");
+	     // Let's not use internal_error() here, otherwise
+	     // empty(test_unknown()) with ABORT_ON_INTERNAL_ERROR defined
+	     // makes Vim abort.
+	     semsg(_(e_intern2), "f_type(UNKNOWN)");
 	     n = -1;
 	     break;
     }

src/testdir/test_functions.vim

@@ -58,6 +58,9 @@ func Test_empty()
 
   call assert_equal(0, empty(function('Test_empty')))
   call assert_equal(0, empty(function('Test_empty', [0])))
+
+  call assert_fails("call empty(test_void())", 'E685:')
+  call assert_fails("call empty(test_unknown())", 'E685:')
 endfunc
 
 func Test_len()

src/testdir/test_vimscript.vim

@@ -1165,6 +1165,8 @@ func Test_type()
     call assert_equal(v:t_none, type(v:none))
     call assert_equal(v:t_none, type(v:null))
 
+    call assert_fails("call type(test_void())", 'E685:')
+    call assert_fails("call type(test_unknown())", 'E685:')
 
     call assert_equal(0, 0 + v:false)
     call assert_equal(1, 0 + v:true)

src/version.c

@@ -738,6 +738,8 @@ static char *(features[]) =
 
 static int included_patches[] =
 {   /* Add new patch number below this line */
+/**/
+    331,
 /**/
     330,
 /**/