Error: spawn solargraph ENOENT

[mikwee]

VSCode constantly says Solargraph's not installed, even though RubyGems shows it is. When I click the "Install Now" button, I get this eror:

[Error - 13:45:51] Starting client failed
Error: spawn solargraph ENOENT
	at notFoundError (c:\Users\mikwee\.vscode-oss\extensions\castwide.solargraph-0.24.0\node_modules\ruby-spawn\node_modules\cross-spawn\lib\enoent.js:6:26)
	at verifyENOENT (c:\Users\mikwee\.vscode-oss\extensions\castwide.solargraph-0.24.0\node_modules\ruby-spawn\node_modules\cross-spawn\lib\enoent.js:40:16)
	at ChildProcess.cp.emit (c:\Users\mikwee\.vscode-oss\extensions\castwide.solargraph-0.24.0\node_modules\ruby-spawn\node_modules\cross-spawn\lib\enoent.js:27:25)
	at Process.ChildProcess._handle.onexit (node:internal/child_process:290:12)

Why?