Fix editor crash when shader has incorrect global array declaration

[jsjtxietian]

Trying to fix #90683

The crash happens around the change in shader_compiler.cpp, in that condition, cnode->array_declarations[0].initializer has size 0 and thus use i=1 to index it will crash the editor. I leave it as a safe guard there.

Note that const bool array[1] = bool[];; will cause the crash but const bool array[1] = bool[]; won't (just trigger Expected a ',' or ';'), the changes I made in shader_language.cpp prevent this by simply don't allow a global const array to be defined without initialization, I checked the doc it didn't say whether it's legal or not, so it might not be a good idea. Feel free to correct me.

[Chaosus]

Also, please add

else {
_set_expected_error("(");
}

after the

godot/servers/rendering/shader_language.cpp

Lines 7359 to 7402 in 4e5ed0b

	if (tk.type == TK_PARENTHESIS_OPEN || curly) { // initialization
	while (true) {
	Node *n = _parse_and_reduce_expression(p_block, p_function_info);
	if (!n) {
	return ERR_PARSE_ERROR;
	}
	if (is_const && n->type == Node::NODE_TYPE_OPERATOR && static_cast<OperatorNode *>(n)->op == OP_CALL) {
	_set_error(RTR("Expected a constant expression."));
	return ERR_PARSE_ERROR;
	}
	if (!_compare_datatypes(var.type, struct_name, 0, n->get_datatype(), n->get_datatype_name(), 0)) {
	return ERR_PARSE_ERROR;
	}
	tk = _get_token();
	if (tk.type == TK_COMMA) {
	decl.initializer.push_back(n);
	continue;
	} else if (!curly && tk.type == TK_PARENTHESIS_CLOSE) {
	decl.initializer.push_back(n);
	break;
	} else if (curly && tk.type == TK_CURLY_BRACKET_CLOSE) {
	decl.initializer.push_back(n);
	break;
	} else {
	if (curly) {
	_set_expected_error("}", ",");
	} else {
	_set_expected_error(")", ",");
	}
	return ERR_PARSE_ERROR;
	}
	}
	if (unknown_size) {
	decl.size = decl.initializer.size();
	var.array_size = decl.initializer.size();
	} else if (decl.initializer.size() != var.array_size) {
	_set_error(RTR("Array size mismatch."));
	return ERR_PARSE_ERROR;
	}
	tk = _get_token();
	}

(its local function case of the same problem)

[akien-mga]

Thanks!