TypeError: Cannot read property 'mime_type' of undefined

[freezy]

View details in Rollbar: https://rollbar.com/freezy/server/items/45/

TypeError: Cannot read property 'mime_type' of undefined
  File "/var/www/server/production/v3.1.3/src/app/files/file.ts", line 127, in Function.getMimeType
    			return file.mime_type;
  File "/var/www/server/production/v3.1.3/src/app/files/file.ts", line 161, in Function.getMimeCategory
    		return mimeTypes[File.getMimeType(file, variation)].category;
  File "/var/www/server/production/v3.1.3/src/app/releases/release.serializer.ts", line 175, in lodash_1.flatten.filter.file
    			.filter(file => File.getMimeCategory(file._file as FileDocument) === 'table');
  File "<anonymous>", line unknown, in Array.filter
  File "/var/www/server/production/v3.1.3/src/app/releases/release.serializer.ts", line 175, in ReleaseSerializer.findThumb
    			.filter(file => File.getMimeCategory(file._file as FileDocument) === 'table');
  File "/var/www/server/production/v3.1.3/src/app/releases/release.serializer.ts", line 135, in ReleaseSerializer.serializeRelease
    			release.thumb = this.findThumb(ctx, doc.versions, opts);
  File "/var/www/server/production/v3.1.3/src/app/releases/release.serializer.ts", line 69, in ReleaseSerializer._simple
    		return this.serializeRelease(ctx, doc, opts,
  File "/var/www/server/production/v3.1.3/src/app/common/serializer.ts", line 179, in ReleaseSerializer.serialize
    		return this._post(ctx, doc, serializer(ctx, doc, this._defaultOpts(opts)), this._defaultOpts(opts));
  File "/var/www/server/production/v3.1.3/src/app/common/serializer.ts", line 57, in ReleaseSerializer.simple
    		return this.serialize(this._simple.bind(this), ctx, doc, opts);
  File "/var/www/server/production/v3.1.3/src/app/releases/release.api.ts", line 301, in results.docs.map.release
    				release = state.serializers.Release.simple(ctx, release, Object.assign({}, qb.getSerializerOpts(), serializerOpts));
  File "<anonymous>", line unknown, in Array.map
  File "/var/www/server/production/v3.1.3/src/app/releases/release.api.ts", line 297, in ReleaseApi.list
    			const releases = results.docs.map(release => {
  File "<anonymous>", line unknown, in <unknown>
  File "internal/process/next_tick.js", line 229, in process._tickDomainCallback [as _tickCallback]