Can't figure out how to debug a package issue

I’m diving into some bug-fixing in Orion 1.4.0. I’ve cloned the packages into my local packages folder so I can easily debug and make edits. I’m getting this error on the Meteor server process:

I20150814-11:35:42.068(-7)? Exception from sub adminGetOne.products id cek3qs7R5uqqiGyBS Error: Match error: Expected string, got object
I20150814-11:35:42.068(-7)?     at checkSubtree (packages/check/match.js:159:1)
I20150814-11:35:42.068(-7)?     at check (packages/check/match.js:32:1)
I20150814-11:35:42.068(-7)?     at [object Object].Meteor.publish.is_auto (packages/orionjs:collections/publications.js:4:1)
I20150814-11:35:42.068(-7)?     at packages/matb33:collection-hooks/collection-hooks.js:218:1
I20150814-11:35:42.068(-7)?     at [object Object]._.extend.withValue (packages/meteor/dynamics_nodejs.js:56:1)
I20150814-11:35:42.068(-7)?     at [object Object]._handler (packages/matb33:collection-hooks/collection-hooks.js:217:1)
I20150814-11:35:42.069(-7)?     at maybeAuditArgumentChecks (packages/ddp/livedata_server.js:1617:1)
I20150814-11:35:42.069(-7)?     at [object Object]._.extend._runHandler (packages/ddp/livedata_server.js:950:1)
I20150814-11:35:42.069(-7)?     at [object Object]._.extend._startSubscription (packages/ddp/livedata_server.js:769:1)
I20150814-11:35:42.069(-7)?     at [object Object]._.extend.protocol_handlers.sub (packages/ddp/livedata_server.js:582:1)
I20150814-11:35:42.069(-7)? Sanitized and reported to the client as: Match failed [400]

I can’t figure out how to trace this. This is obviously coming from Orion, yet I don’t see any of Orion’s source files mentioned anywhere. How can I figure out where this problem is occurring?