Better argument validation for some list methods.

test/number/divide_operand_not_num.wren

@@ -0,0 +1 @@
+1 / false // expect runtime error: Right operand must be a number.

test/number/divide_wrong_argument_type.wren

@@ -1 +0,0 @@
-1 / false // expect runtime error: TypeError: Right operand must be Num.

test/number/minus_operand_not_num.wren

@@ -0,0 +1 @@
+1 - false // expect runtime error: Right operand must be a number.

test/number/minus_wrong_argument_type.wren

@@ -1 +0,0 @@
-1 - false // expect runtime error: TypeError: Right operand must be Num.

test/number/mod_operand_not_num.wren

@@ -0,0 +1 @@
+1 % false // expect runtime error: Right operand must be a number.

test/number/mod_wrong_argument_type.wren

@@ -1 +0,0 @@
-1 % false // expect runtime error: TypeError: Right operand must be Num.

test/number/multiply_operand_not_num.wren

@@ -0,0 +1 @@
+1 * false // expect runtime error: Right operand must be a number.

test/number/multiply_wrong_argument_type.wren

@@ -1 +0,0 @@
-1 * false // expect runtime error: TypeError: Right operand must be Num.

test/number/plus_operand_not_num.wren

@@ -0,0 +1,3 @@
+1 + false // expect runtime error: Right operand must be a number.
+
+// TODO: What about a string on the RHS?

test/number/plus_wrong_argument_type.wren

@@ -1,3 +0,0 @@
-1 + false // expect runtime error: TypeError: Right operand must be Num.
-
-// TODO: What about a string on the RHS?