Fix NPE in emoji filter and enforce Locale.ROOT for case folding

[Copilot]

performFiltering called charSequence.toString() before the null check, risking an NPE on framework-initiated filter calls with a null constraint. Additionally, toLowerCase() without a locale was used in both the filter and getLowerShortcode(), making matching locale-sensitive.

Changes

• CustomEmojiPopupKeyboard.java — performFiltering

  • Moved null/empty guard before charSequence.toString(); search is now computed only inside the else branch
  • Switched to toLowerCase(Locale.ROOT)
  • Added import java.util.Locale

• Emoji.java — getLowerShortcode()

  • Switched cached value to shortcode.toLowerCase(Locale.ROOT) so both sides of the contains() check use the same locale
  • Added import java.util.Locale

// Before — NPE if charSequence is null
String search = charSequence.toString().toLowerCase().trim();
if (charSequence == null || charSequence.length() == 0) { ... }

// After — null-safe, locale-invariant
if (charSequence == null || charSequence.length() == 0) {
    filteredEmoji.addAll(originalCategory.emojis);
} else {
    String search = charSequence.toString().toLowerCase(Locale.ROOT).trim();
    ...
}

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[Copilot]

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• dl.google.com
  • Triggering command: /usr/lib/jvm/temurin-17-jdk-amd64/bin/java /usr/lib/jvm/temurin-17-jdk-amd64/bin/java --add-opens=java.base/java.lang=ALL-UNNAMED --add-opens=java.base/java.lang.invoke=ALL-UNNAMED --add-opens=java.base/java.util=ALL-UNNAMED --add-opens=java.prefs/java.util.prefs=ALL-UNNAMED --add-exports=jdk.compiler/com.sun.tools.javac.api=ALL-UNNAMED --add-exports=jdk.compiler/com.sun.tools.javac.util=ALL-UNNAMED --add-opens=java.base/java.util=ALL-UNNAMED --add-opens=java.prefs/java.util.prefs=ALL-UNNAMED --add-opens=java.base/java.nio.charset=ALL-UNNAMED --add-opens=java.base/java.net=ALL-UNNAMED --add-opens=java.base/java.util.concurrent.atomic=ALL-UNNAMED --add-opens=java.xml/javax.xml.namespace=ALL-UNNAMED -Xmx2048m -Dfile.encoding=UTF-8 -Duser.country -Duser.language=en -Duser.variant -cp /home/REDACTED/.gradle/wrapper/dists/gradle-8.11.1-bin/bpt9gzteqjrbo1mjrsomdt32c/gradle-8.11.1/lib/gradle-daemon-main-8.11.1.jar (dns block)

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