In Tcl_GetNumberFromObj() change the dictionary length check from > 1…

… to > 0 to

determine whether the value can be parsed as a number, and make corresponding
changes in tclObj.c and expr.test.

generic/tclExecute.c

@@ -9112,7 +9112,7 @@ IllegalExprOperandType(
 	Tcl_Size length;
 	if (TclHasInternalRep(opndPtr, &tclDictType)) {
 	    Tcl_DictObjSize(NULL, opndPtr, &length);
-	    if (length > 1) {
+	    if (length > 0) {
 	    listRep:
 		Tcl_SetObjResult(interp, Tcl_ObjPrintf(
 			"cannot use a list as %soperand of \"%s\"", ord, op));

generic/tclObj.c

@@ -3708,7 +3708,7 @@ Tcl_GetNumberFromObj(
 	/* Handle dict separately, because it doesn't have a lengthProc */
 	if (TclHasInternalRep(objPtr, &tclDictType)) {
 	    Tcl_DictObjSize(NULL, objPtr, &length);
-	    if (length > 1) {
+	    if (length > 0) {
 	    listRep:
 		if (interp) {
 		    Tcl_SetObjResult(interp, Tcl_NewStringObj("expected number but got a list", -1));

tests/expr.test

@@ -509,7 +509,7 @@ test expr-11.15 {CompileAddExpr: runtime error} {
 } {1 {cannot use non-numeric string "1 2 3" as left operand of "+"}}
 test expr-11.16 {CompileAddExpr: runtime error} {
     list [catch {expr {~[dict create foo bar]}} msg] $msg
-} {1 {cannot use non-numeric string "foo bar" as operand of "~"}}
+} {1 {cannot use a list as operand of "~"}}
 
 test expr-12.1 {CompileMultiplyExpr: just unary expr} {expr ~4} -5
 test expr-12.2 {CompileMultiplyExpr: just unary expr} {expr --5} 5