small bug fix, check changelog tab

app.py

@@ -219,16 +219,19 @@ def check_for_remaining_wav_or_mp3_files(which_filetype):
     return f"There are {len(audio_files)} leftover files."
 
 def display_audio_spectrogram(audio_file):
-    y, sr = librosa.load(audio_file)
-    d = librosa.amplitude_to_db(np.abs(librosa.stft(y)), ref=np.max)
-    plt.figure(figsize=(12, 8))
-    librosa.display.specshow(d, sr=sr, x_axis="time", y_axis="log")
-    plt.colorbar(format="%+2.0f db")
-    plt.title("Spectrogram")
-    output = "spectrogram.png"
-    plt.savefig(output)
-    plt.close()
-    return output
+    if audio_file == None:
+        raise gr.Error("Cannot leave WAV field empty! Please insert a WAV file.")
+    else:
+        y, sr = librosa.load(audio_file)
+        d = librosa.amplitude_to_db(np.abs(librosa.stft(y)), ref=np.max)
+        plt.figure(figsize=(12, 8))
+        librosa.display.specshow(d, sr=sr, x_axis="time", y_axis="log")
+        plt.colorbar(format="%+2.0f db")
+        plt.title("Spectrogram")
+        output = "spectrogram.png"
+        plt.savefig(output)
+        plt.close()
+        return output
 
 with gr.Blocks(theme='sudeepshouche/minimalist', title="Global Dataset Maker") as app:
     gr.HTML(
@@ -351,6 +354,7 @@ with gr.Blocks(theme='sudeepshouche/minimalist', title="Global Dataset Maker") a
                         gr.Image(label="Spectrogram result", show_download_button=False, scale=2)
                     )
         with gr.TabItem("Changelog"):
+            gr.Markdown("v0.97a - Fixed issue with spectrogram tab if no WAV file was selected.")
             gr.Markdown("v0.97 - Added new spectrogram tool in Misc Tools and removed pitch analyzer as it did not fit with the purpose of this Space.")
             gr.Markdown("v0.96 - Added new remaining files tool in Misc Tools.")
             gr.Markdown("v0.95 - Fixed issue with mp3 files not downloading audio properly.")