Relax VALUE parsing for nextcloud bug.

src/parser.rs

@@ -280,8 +280,15 @@ impl<'s> VcardParser<'s> {
                             params.language = Some(tag);
                         }
                         VALUE => {
-                            let value: ValueType = value.parse()?;
-                            params.value = Some(value);
+                            if self.strict {
+                                let value: ValueType = value.parse()?;
+                                params.value = Some(value);
+                            } else {
+                                if let Ok(value) = value.parse::<ValueType>()
+                                {
+                                    params.value = Some(value);
+                                }
+                            }
                         }
                         PREF => {
                             let value: u8 = value.parse()?;

tests/parameters.rs

@@ -8,7 +8,7 @@ use vcard4::{
         Pid, RelatedType, TelephoneType, TimeZoneParameter, TypeParameter,
         ValueType,
     },
-    parse, Error,
+    parse, parse_loose, Error,
 };
 
 use test_helpers::{assert_language, assert_media_type, assert_round_trip};
@@ -368,3 +368,18 @@ END:VCARD"#;
 
     Ok(())
 }
+
+// SEE: https://github.com/tmpfs/vcard4/issues/21
+#[test]
+fn param_nextcloud_ignore_bad_value() -> Result<()> {
+    let input = r#"BEGIN:VCARD
+VERSION:3.0
+FN:Example Card2
+TEL;TYPE=CELL;VALUE=UNKNOWN:+01555123456
+END:VCARD"#;
+
+    assert!(parse(input).is_err());
+    assert!(parse_loose(input).is_ok());
+
+    Ok(())
+}