Fix NS_BASE_STREAM_CLOSED error, for real

The input stream produced by asyncFetch is closed automatically at EOL,
so the available() call throws this for an empty file.

chrome/content/zotero/xpcom/file.js

@@ -221,7 +221,17 @@ Zotero.File = new function(){
 			}
 			
 			try {
-				var bytesToFetch = inputStream.available();
+				try {
+					var bytesToFetch = inputStream.available();
+				}
+				catch (e) {
+					// The stream is closed automatically when end-of-file is reached,
+					// so this throws for empty files
+					if (e.name == "NS_BASE_STREAM_CLOSED") {
+						deferred.resolve("");
+					}
+				}
+				
 				if (maxLength && maxLength < bytesToFetch) {
 					bytesToFetch = maxLength;
 				}

test/tests/fileTest.js

@@ -1,4 +1,11 @@
 describe("Zotero.File", function () {
+	describe("#getContentsAsync()", function () {
+		it("should handle an empty file", function* () {
+			var path = OS.Path.join(getTestDataDirectory().path, "empty");
+			assert.equal((yield Zotero.File.getContentsAsync(path)), "");
+		})
+	})
+	
 	describe("#copyDirectory()", function () {
 		it("should copy all files within a directory", function* () {
 			var tmpDir = Zotero.getTempDirectory().path;

test/tests/translateTest.js

@@ -378,11 +378,6 @@ describe("Zotero.Translate.ItemGetter", function() {
 			}
 		}));
 		
-		// TEMP
-		describe("failure debugging", function () {
-		before(() => Zotero.Debug.init(true))
-		after(() => Zotero.Debug.init())
-		
 		it('should return stored/linked file and URI attachments in expected format', Zotero.Promise.coroutine(function* () {
 			this.timeout(60000);
 			let file = getTestDataDirectory();
@@ -591,7 +586,5 @@ describe("Zotero.Translate.ItemGetter", function() {
 				}
 			}
 		}));
-		
-		})
 	});
 });