fix: allow undefined color in toolbox definition (#5801)
fix: allow undefined color in toolbox definition (#5801)


mark-friedman/blockly,rachel-fenichel/blockly,rachel-fenichel/blockly,google/blockly,mark-friedman/blockly,google/blockly,google/blockly,mark-friedman/blockly,google/blockly,rachel-fenichel/blockly,rachel-fenichel/blockly,rachel-fenichel/blockly,rachel-fenichel/blockly,google/blockly,mark-friedman/blockly,rachel-fenichel/blockly,google/blockly,mark-friedman/blockly,google/blockly,mark-friedman/blockly