node_modules has this file
Think the answer is the same as your other question:
Grafana cannot build a plugin and the plugin runs inside Grafana so your 3rd party code is not in Grafana’s node_modules directory. You need to copy any code needed from the plugin’s node_modules directory into the plugin source directory.
I have the same problem as you. Is your solution solved? can you help me?
you can put the echarts.js file into the panel src ,and import it in the ctrl.js,like this ,finally, change the grunfile.js to build the js to dist,