Fix template string

[styfle]

This PR contains:

• bugfix

Are tests included?

• yes (bugfixes and features will not be merged without tests)

Breaking Changes?

• no

List any relevant issue numbers:

Description

This error message should probably use a template string so that pluginName is not a literal but it's value is printed instead.

[styfle]

Should I add one more assert to check the error message string includes the plugin name?

rollup/test/hooks/index.js

Line 846 in 138033e

assert.equal(err.pluginCode, 'DUPLICATE_PLUGIN_NAME');

Maybe something like assert.equal(err.message.includes(plugin), true);

[shellscape]

@styfle nice catch! yes, please do add a test. definitely would not hurt.

[styfle]

@shellscape Done!

[shellscape]