ignore "Undefined" EXIF values during extraction

src/extractors/photo.rs

@@ -13,7 +13,7 @@ use anyhow::{anyhow, Result};
 
 pub struct ExifExtractor;
 
-// TODO: EXIF metadata is oftentimes a constant/enum value. What's the proper 
+// TODO: EXIF metadata is oftentimes a constant/enum value. What's the proper
 //       model for enum-like values in UpEnd?
 
 impl Extractor for ExifExtractor {
@@ -60,6 +60,7 @@ impl Extractor for ExifExtractor {
 
                 let result: Vec<Entry> = exif
                     .fields()
+                    .filter(|field| !matches!(field.value, exif::Value::Undefined(..)))
                     .flat_map(|field| {
                         if let Some(tag_description) = field.tag.description() {
                             let attribute = format!("EXIF_{}", field.tag.1);