3 files changed, 27 insertions, 34 deletions

diff --git a/src/data/things/art-tag.js b/src/data/things/art-tag.js
index 0f888a20..9a8a75c5 100644
--- a/src/data/things/art-tag.js
+++ b/src/data/things/art-tag.js
@@ -25,7 +25,6 @@ export class ArtTag extends Thing {
 
     // Expose only
 
-    // Previously known as: (tag).things
     taggedInThings: {
       flags: {expose: true},
 
diff --git a/src/data/things/track.js b/src/data/things/track.js
index c59c9303..6b1e958b 100644
--- a/src/data/things/track.js
+++ b/src/data/things/track.js
@@ -91,7 +91,6 @@ export class Track extends Thing {
       },
     },
 
-    // Previously known as: (track).aka
     originalReleaseTrackByRef: Thing.common.singleReference(Track),
 
     dataSourceAlbumByRef: Thing.common.singleReference(Album),
@@ -241,7 +240,6 @@ export class Track extends Thing {
       },
     },
 
-    // Previously known as: (track).artists
     artistContribs: Thing.common.dynamicInheritContribs(
       'artistContribsByRef',
       'artistContribsByRef',
@@ -249,10 +247,8 @@ export class Track extends Thing {
       Track.findAlbum
     ),
 
-    // Previously known as: (track).contributors
     contributorContribs: Thing.common.dynamicContribs('contributorContribsByRef'),
 
-    // Previously known as: (track).coverArtists
     coverArtistContribs: Thing.common.dynamicInheritContribs(
       'coverArtistContribsByRef',
       'trackCoverArtistContribsByRef',
@@ -260,7 +256,6 @@ export class Track extends Thing {
       Track.findAlbum
     ),
 
-    // Previously known as: (track).references
     referencedTracks: Thing.common.dynamicThingsFromReferenceList(
       'referencedTracksByRef',
       'trackData',
@@ -312,7 +307,6 @@ export class Track extends Thing {
       },
     },
 
-    // Previously known as: (track).flashes
     featuredInFlashes: Thing.common.reverseReferenceList(
       'flashData',
       'featuredTracks'
diff --git a/src/data/yaml.js b/src/data/yaml.js
index befd362a..f269d447 100644
--- a/src/data/yaml.js
+++ b/src/data/yaml.js
@@ -963,7 +963,7 @@ export async function loadAndProcessDataDocuments({dataPath}) {
             });
           } else {
             const {result, aggregate} = mapAggregate(
-              yamlResult,
+              yamlResult.filter(Boolean),
               decorateErrorWithIndex(dataStep.processDocument),
               {message: `Errors processing documents`});
             processResults = result;
@@ -989,7 +989,7 @@ export async function loadAndProcessDataDocuments({dataPath}) {
           typeof dataStep.files === 'function'
             ? await callAsync(dataStep.files, dataPath)
             : dataStep.files
-        )
+        );
 
         if (!files) {
           return;
@@ -1000,8 +1000,7 @@ export async function loadAndProcessDataDocuments({dataPath}) {
         const readResults = await mapAsync(
           files,
           (file) => readFile(file, 'utf-8').then((contents) => ({file, contents})),
-          {message: `Errors reading data files`}
-        );
+          {message: `Errors reading data files`});
 
         const yamlResults = map(
           readResults,
@@ -1009,8 +1008,7 @@ export async function loadAndProcessDataDocuments({dataPath}) {
             file,
             documents: yaml.loadAll(contents),
           })),
-          {message: `Errors parsing data files as valid YAML`}
-        );
+          {message: `Errors parsing data files as valid YAML`});
 
         let processResults;
 
@@ -1021,12 +1019,17 @@ export async function loadAndProcessDataDocuments({dataPath}) {
             yamlResults.forEach(({file, documents}) => {
               const [headerDocument, ...entryDocuments] = documents;
 
+              if (!headerDocument) {
+                call(decorateErrorWithFile(() => {
+                  throw new Error(`Missing header document (empty file or erroneously starting with "---"?)`);
+                }), {file});
+                return;
+              }
+
               const header = call(
                 decorateErrorWithFile(({document}) =>
-                  dataStep.processHeaderDocument(document)
-                ),
-                {file, document: headerDocument}
-              );
+                  dataStep.processHeaderDocument(document)),
+                {file, document: headerDocument});
 
               // Don't continue processing files whose header
               // document is invalid - the entire file is excempt
@@ -1036,14 +1039,13 @@ export async function loadAndProcessDataDocuments({dataPath}) {
               }
 
               const entries = map(
-                entryDocuments.map((document) => ({file, document})),
+                entryDocuments
+                  .filter(Boolean)
+                  .map((document) => ({file, document})),
                 decorateErrorWithFile(
                   decorateErrorWithIndex(({document}) =>
-                    dataStep.processEntryDocument(document)
-                  )
-                ),
-                {message: `Errors processing entry documents`}
-              );
+                    dataStep.processEntryDocument(document))),
+                {message: `Errors processing entry documents`});
 
               // Entries may be incomplete (i.e. any errored
               // documents won't have a processed output
@@ -1061,22 +1063,20 @@ export async function loadAndProcessDataDocuments({dataPath}) {
 
             yamlResults.forEach(({file, documents}) => {
               if (documents.length > 1) {
-                call(
-                  decorateErrorWithFile(() => {
-                    throw new Error(
-                      `Only expected one document to be present per file`
-                    );
-                  })
-                );
+                call(decorateErrorWithFile(() => {
+                  throw new Error(`Only expected one document to be present per file`);
+                }), {file});
                 return;
+              } else if (empty(documents) || !documents[0]) {
+                call(decorateErrorWithFile(() => {
+                  throw new Error(`Expected a document, this file is empty`);
+                }), {file});
               }
 
               const result = call(
                 decorateErrorWithFile(({document}) =>
-                  dataStep.processDocument(document)
-                ),
-                {file, document: documents[0]}
-              );
+                  dataStep.processDocument(document)),
+                {file, document: documents[0]});
 
               if (!result) {
                 return;